Method for contracting or crimping stents

ABSTRACT

An apparatus for manipulating a medical device is formed of at least three coupled movable blades which are disposed about a reference circle to form an aperture whose size may be varied. The aperture capable of being sized to contain a medical device. Each blade is in communication with an actuation device which is capable of moving the blade to alter the size of the aperture. Each blade includes a single radial point which a) lies on the circumference of the reference circle prior to movement of the blade, and b) may be moved only along a radius of the reference circle on movement of the blade.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/537,044, filed Aug. 6, 2009, issued as U.S. Pat. No. 7,992,273 B2,which is a continuation of Ser. No. 11/159,490, filed Jun. 23, 2005,issued as U.S. Pat. No. 7,587,801, which is a continuation of U.S.patent application Ser. No. 10/444,807, filed on May 23, 2003, issued asU.S. Pat. No. 6,915,560, which is a divisional of U.S. patentapplication Ser. No. 09/966,686, filed on Oct. 1, 2001, issued as U.S.Pat. No. 6,823,576, which is a continuation of U.S. patent applicationSer. No. 09/401,218, filed on Sep. 22, 1999, issued as U.S. Pat. No.6,360,577, which are all herein incorporated by reference.

BACKGROUND OF THE INVENTION

This invention relates to an apparatus and a method for reducing in sizea medical device such as a stent, stent-graft, graft, or vena cavafilter. The apparatus may be used in particular for fastening a medicaldevice onto a catheter.

Medical devices such as stents, stent-grafts, grafts, or vena cavafilters and catheters for their delivery are utilized in a number ofmedical procedures and situations, and as such their structure andfunction are well known.

A stent, for example, is a generally cylindrical prosthesis introducedvia a catheter into a lumen of a body vessel in a configuration having agenerally reduced diameter and then expanded to the diameter of thevessel. In its expanded configuration, the stent supports and reinforcesthe vessel walls while maintaining the vessel in an open, unobstructedcondition.

Stents are typically inflation expandable or self-expanding. Selfexpanding stents which are constrained by a sheath or other restrainingmeans, must be provided in a reduced diameter.

An example of a stent described in PCT Application No. 960 3092 A1,published 8 Feb. 1996.

In advancing a stent through a body vessel to the deployment site, thestent must be able to securely maintain its axial position on thedelivery catheter, without translocating proximally or distally, andespecially without becoming separated from the catheter. Stents that arenot properly secured or retained to the catheter may slip and either belost or be deployed in the wrong location. The stent must be crimped insuch a way as to minimize or prevent altogether distortion of the stentand to thereby prevent abrasion and/or reduce trauma of the vesselwalls.

In the past, this crimping or size reduction has been done by hand oftenresulting in the application of undesired uneven forces to the stent.Such a stent must either be discarded or re-crimped. Stents which havebeen crimped or otherwise reduced in size multiple times can suffer fromfatigue and may be scored or otherwise marked which can causethrombosis. A poorly crimped stent can also damage the underlyingballoon.

Recently, stent crimping devices have been disclosed in U.S. Pat. No.5,546,646 to Williams et al, U.S. Pat. No. 5,183,085 to Timmermans etal., U.S. Pat. No. 5,626,604 to Cottone, Jr., U.S. Pat. No. 5,725,519,U.S. Pat. No. 5,810,873 to Morales, WO 97/20593 and WO 98/19633.

A cam actuated stent crimper, shown in FIG. 1, employs a plurality ofarc-shaped or curved slots with semi-circular ends, disposed such thateach slot or cam engages a cam follower bearing 22. The arc-shaped orcurved surfaces of the slots are inclined to be non-concentric relativeto the axis of rotation 26, and therefore rotation of the cam plate 28transmits equal radial displacements to the cam follower bearings 22, tosimultaneously actuate a like number of linear bearings 24, which havetheir corresponding linear tracks or rails mounted on a fixed plate. Asshown in FIG. 1 the cam plate rotary drive 29 comprises a pneumaticcylinder mounted on a pivot or trunnion, arranged with the cylinder rodconnected rotatably to a short arm fixed rigidly to the cam plate.Accordingly, linear motion produced by the pneumatic cylinder translatesinto controllable arcs of motion of the circular cam plate, which has aprojecting V-shaped profile on its outer edge in rolling engagement withthree equally spaced rollers with mating inverse V-shaped profiles toprovide precise rotatable support to the cam plate. Depending on thedirection of rotation, the linear slides which each carry a radiallydisposed crimping blade, are either moved inwards to apply a crimpingforce to the stent, or outwards to release the stent. Also whencrimping, depending on the degree of rotation of the cam plate, aspecific radial crimping displacement may be obtained to match thediametral reduction required for any particular stent.

All US patents and applications and all other published documentsmentioned anywhere in this application are incorporated herein byreference in their entirety.

BRIEF SUMMARY OF THE INVENTION

It would be desirable to produce a device capable of crimping a stentuniformly while minimizing the distortion of and scoring and marking ofthe stent due to the crimping. The present invention is directed to thatend.

The present invention is particularly concerned with the crimping andotherwise reducing in size of inflation expandable stents,self-expanding stents and other expandable medical devices. For thepurpose of this disclosure, it is understood that the term ‘stent’includes stents, stent-grafts, grafts and vena cava filters. It is alsounderstood that the term ‘crimping’ refers to a reduction in size orprofile of a stent.

In the description that follows it is understood that the inventioncontemplates crimping a medical device either directly to a cathetertube or to a catheter balloon which is disposed about a catheter tube.When reference is made to crimping a medical device to a catheter, aballoon may be situated between the medical device and the catheter tubeor the medical device may be crimped to a region of a catheter tubedirectly. The invention also contemplates crimping a stent in theabsence of a catheter to reduce the stent in size.

The present invention is directed, in one embodiment, to an apparatusfor reducing a medical device in size. Desirably, the medical device isa stent, a stent-graft, a graft or a vena cava filter, whetherself-expandable, balloon expandable or otherwise expandable, althoughthe inventive apparatus may also be employed with any other suitable,generally tubular medical device which must be reduced in size.

The inventive apparatus comprises at least three coupled movable bladesdisposed about a reference circle to form an aperture whose size may bevaried. Each blade is in communication with an actuation device which iscapable of moving the blade to alter the size of the aperture. Eachblade includes a single radial point on the surface of the blade whicha) lies on the circumference of the reference circle prior to movementof the blade, and b) may be moved only along a radius of the referencecircle on movement of the blade.

The apparatus further includes an actuation device which comprises a camand a plurality of linear slide devices. Each linear slide device is incommunication with a blade. Each of the linear slide devices is also inmechanical communication with the cam. Rotation of the cam results inlinear translation of the slide device and blade, such that the slidedevice moves along an axis parallel to the radius on which the radialpoint of the blade lies or along the radius itself.

The invention is also directed to an apparatus similar to that describedabove, with blades disposed about a reference tube to form a tubularaperture whose size may be varied. Each blade is in communication withan actuation device which is capable of moving the blade to alter thesize of the tubular aperture. Each blade includes a single line which a)lies on the surface of the reference tube prior to movement of theblade, and b) may be moved only along a radial plane of the referencetube on movement of the blade.

The inventive apparatus finds particular utility in crimping a medicaldevice such as those mentioned above to a catheter or to a balloondisposed about a catheter.

The inventive apparatus also finds utility in reducing the diameter of amedical device such as those mentioned above prior to crimping.

The invention is also directed to a method of manipulating a medicaldevice which comprises the steps of providing the medical device andproviding at least three blades capable of applying a radial inwardforce. The blades are disposed about a reference circle to form ashrinkable aperture. A medical device such as a stent is placed into theshrinkable aperture and the blades simultaneously moved inward to applya radial inward force to the medical device. The blades are constructedand arranged such that each blade has a single point which a) lies onthe circumference of the reference circle prior to movement of theblade, and b) is moved along a radius of the reference circle onmovement of the blade.

The inventive apparatus may also be used as a variable size balloonmold. To that end, the invention is further directed to a method ofmolding a medical balloon. In the practice of the method, a balloonpreform prepared through any suitable technique known in the art isprovided. The preform is placed in an apparatus which has a shrinkabletubular aperture formed by at least three movable blades disposed abouta reference tube. The blades are constructed and arranged such that eachblade has a single line which a) lies on the surface of the referencetube prior to movement of the blade, and b) is moved along a radialplane of the reference tube on movement of the blade. The aperture maybe set to a predetermined size prior to placement of the preform thereinor after placement of the preform therein. An inflation fluid issupplied to the balloon preform to expand the balloon preform until itcontacts the blades. The preform may optionally be heated prior to,during or after the blowing step. The thus formed balloon is thenpressure relieved and removed from the apparatus.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

FIG. 1 shows a perspective view of a stent crimper;

FIG. 2 a is a schematic front view of an embodiment of the inventiveapparatus;

FIG. 2 b is a schematic front view of the embodiment of FIG. 2 a afterthe stent has been reduced in size;

FIGS. 3 a and 3 b are schematics of blades;

FIG. 3 c is a partial schematic front view of an embodiment of theinventive apparatus employing the curved blades of FIG. 3 b;

FIG. 4 a is a partial front view of an embodiment of the inventiveapparatus;

FIG. 4 b is a partial front view of an embodiment of the inventiveapparatus;

FIG. 4 c shows a side view of the embodiment of FIG. 4 b taken alonglines 4 c-4 c;

FIG. 5 a shows a partial front view of another embodiment of theinventive apparatus;

FIG. 5 b shows a link connected to a blade;

FIG. 6 is a schematic, perspective view of an embodiment of theinventive apparatus;

FIG. 7 shows a partial view of the embodiment of FIG. 6;

FIGS. 8 a and 8 b are partial side elevational views of an embodiment ofthe inventive apparatus taken along a radial plane during the sizereduction process;

FIG. 8 c is a partial side elevational view of an embodiment of theinventive apparatus taken along a radial plane following crimping of astent to a catheter;

FIG. 9 is a diagrammatic side elevational view of an embodiment of theinventive apparatus;

FIG. 10 is a partial side elevational view of an embodiment of theinventive apparatus taken along a radial plane of an embodiment of theinvention consisting of three individual apparatuses arrangedsequentially;

FIG. 11 is a schematic showing a stent being reduced in size and loadedinto a sheath;

FIG. 12 is a partial side elevational view of an embodiment of theinventive apparatus taken along a radial plane showing a balloon thathas been molded with the inventive device; and

FIG. 13 is a partial side elevational view taken along a radial plane 5showing a stepped balloon that has been molded with the inventivedevice.

DETAILED DESCRIPTION OF THE INVENTION

While this invention may be embodied in many different forms, there aredescribed in detail herein specific preferred embodiments of theinvention. This description is an exemplification of the principles ofthe invention and is not intended to limit the invention to theparticular embodiments illustrated.

As shown generally at 100 in FIGS. 2 a and 2 b, the inventive apparatuscomprises eight coupled blades 106 disposed about a reference circle 114to form an aperture 118 whose size may be varied. The apparatus maycomprise as few as three blades and as many as sixteen or more blades.Desirably, the apparatus will have four or more blades and moredesirably, eight or more blades. The maximum number of blades is limitedonly by how many blades can physically be coupled together under therelevant size constraints. As the number of blades is increased, theprofile of the aperture and hence of the medical device followingreduction in size, becomes smoother. FIG. 2 b shows the apparatus ofFIG. 2 a after the stent has been reduced in size.

Blades 106 as shown in FIG. 3 a have an inner end 108 which is desirablybeveled 111 so as to mesh with adjacent blades and an outer end 110which is displaced from aperture 118. Aperture 118 is polygonal. Blades106 may also be shaped with a curved end 112, as shown in FIGS. 3 b and3 c so as to form a substantially circular shaped aperture, when theaperture is fully closed.

Each blade 106 includes a single radial point 122 which lies on a radialline 126 of reference circle 114 prior to movement of blade 106 andwhich may be moved only along the radius 126 of reference circle 114 onmovement of blade 106. Desirably, the single radial point 122 will bedisposed at the tip of the blade adjacent to beveled end 111.

In the embodiment shown in FIG. 4 a, radial point 122 lies at the tip ofblade 106. Each blade 106 has a connecting link 130 extending fromsecond end 110. Connecting link 130 ends in mounting means 134,typically a mounting flange adapted for attachment to a linear bearingblock, for interfacing with an actuation device, shown generally at 138.Actuation device 138 is capable of simultaneously moving blades 106 toalter the size of aperture 118.

Actuation device 138 includes actuation plate 142 which is coaxial withreference circle 114. Actuation plate 142 has eight equi-spaced radialslots 146. More generally, for every blade there will be a correspondingradial slot on actuation plate 142. Each radial slot 146 overlaps amounting means 134 for a linear bearing block at the end of a connectinglink 130. Each blade 106 is engaged to actuation plate 142 via a camfollower bearing 150 disposed in radial slot 146 and attached tomounting means in slotted end 134.

Each bearing 150 extends from a linear slide 154. Linear slide 154 ismounted on a non-rotating plate 156 (shown in FIG. 8). Linear slide 154is constructed and arranged to slide along a line 158 which is parallelto the radius 126 on which radial point 122 of blade 106 lies.

For the purposes of this disclosure, the term ‘cam follower bearing’includes cam follower bearings, low friction rollers, roller bearings,needle roller bearings and a slipper block pivot mounted on a bearingand stub shaft. FIG. 4 b is a partial front view of an embodiment inwhich a slipper block is used. A side view of the embodiment of FIG. 4 btaken along lines 4 c-4 c is shown in FIG. 4 c. Slipper block 150resides in slot 146 of actuation plate 142. Slipper block 150 is mountedon stub shaft 151 which extends from connecting link 130. Desirably,bearings 153 will be present between shaft 151 and slipper block 150.Connecting link 130, in turn, is fastened to linear bearing block 212via fasteners 214. Bearing block 212 is linearly mounted on linear slidewhich is mounted on fixed plate 156. Linear motion is facilitated by thepresence of bearings 216.

Cam follower bearing 150 may be replaced by any other suitableconnecting member which can connect the slide and the link.

In use, as actuation plate 142 is rotated in a clockwise direction, theclockwise motion of the actuation plate is translated into linear motionof each of linear slide 154 and blade 106 via bearing 150. Each blade106 moves outward in a direction parallel to the radius 126 on which theradial point 122 of the blade 106 lies, resulting in the opening ofaperture 118. As actuation plate 142 is rotated in a counterclockwisedirection, each blade 106 moves inward in a direction parallel to theradius 126 on which the radial point 122 of the blade 106 lies,resulting in the closing of aperture 118. As aperture 118 closes, aradially inward force is applied to a medical device disposed in theaperture. The actuation plate is rotated until the desired sizereduction of the aperture and medical device has been achieved.Following the reduction, the actuation plate is rotated in the oppositedirection to allow for removal of the medical device from the aperture.

The apparatus may be used to reduce the diameter of a suitable medicaldevice such as those disclosed above or may be used to crimp a medicaldevice to a catheter.

Another embodiment of the invention is shown in FIG. 5 a. Each blade106, as shown in FIG. 5 a, has a connecting link 130 extendingtherefrom. Connecting link 130 is rigidly attached to blade 106.Connecting link 130 ends in an angled end 134 for interfacing with anactuation device, shown generally at 138. Actuation device 138 iscapable of simultaneously moving blades 106 to alter the size ofaperture 118.

Actuation device 138 includes a rotatable actuation plate 142 which isco-axial with reference circle 114. Rotatable actuation plate includescam slots 146 which are not concentric with the axis of rotation, arcinginward. Each connecting link 130 is engaged to actuation plate 146 via acam follower bearing 150 disposed in slot 146 and attached to bothangled end 134 of connecting link 130 and to a linear slide 154. Linearslide 154 is mounted on a non-rotating plate similar to that shown inFIG. 8. Linear slide 154 is constructed and arranged to slide along aradial line 158 on which radial point 122 of blade 106 lies.

Connecting link 130 may be bonded adhesively, welded, joined with afastener or otherwise joined to blade 106. As shown in FIG. 5 a, asingle screw 131 is used to connect link 130 to blade 106. FIG. 5 bshows a connecting link 130 including a right angle portion which isfastened to a blade 106 using two screws 131. Connecting link 130 andblade 106 may optionally be formed of a single piece of material.Regardless of how the connecting member is joined to the blade, nomovement of the blade relative to the connecting link is permitted.

In use, as actuation plate 142 is rotated in a clockwise direction, theclockwise motion of the actuation plate is translated into a linearoutward motion of each of linear slides 154 and blades 106 via bearings150 resulting in the opening of aperture 118. The outward motion resultsfrom the radially outward arcing of cam slot 146. As actuation plate 142is rotated in a counterclockwise direction, each blade 106, because ofthe radially inward arc of cam slots 146, moves inward in a directionparallel to the radius 126 on which the radial point 122 of the blade106 lies, resulting in the closing of aperture 118. As discussed above,as the aperture is decreased in size, a radial inward force is broughtto bear against a medical device disposed in the aperture, therebyreducing the size of the medical device.

The embodiment of FIG. 5 a differs from the embodiment of FIG. 4 a inthat in the embodiment of FIG. 5 a, the slide moves along the radialline on which the radial point of the attached blade lies whereas inFIG. 4 a the slide moves parallel to the radial line. In both of theembodiments, each of the blades is constrained with two degrees offreedom to satisfy the condition that the movement of the tip be radialin accordance with the invention.

In the embodiments of FIGS. 4 a and 5 a, the slots in the actuationplate are constructed and arranged to allow for a sufficient reductionin size of the aperture so that a medical device can be reduced in sizeto a desired diameter. Those of ordinary skill in the art will recognizeother suitable actuation devices that may be used in the practice ofthis invention.

Desirably, in the above embodiments, the blades will be as long as orlonger than the medical device disposed within so that the medicaldevice is uniformly reduced in size along its entire length.

This is illustrated in the embodiment of FIGS. 6 and 7 and further inFIGS. 3 a and 3 b in which blades 106 are disposed about a referencetube 160 to form a tubular aperture 162 whose size may be varied.Reference circle 114 is seen to lie along reference tube 160. Each blade106 is in communication with an actuation device such as that shown inFIG. 4 or 5. The actuation device is capable of moving blades 106 toalter the size of tubular aperture 162. Each blade 106 includes a singleline 166 which a) lies on a radial plane 170 of the reference tube 160prior to movement of blade 106, and b) may be moved only along a radialplane 170 of reference tube 160 on movement of blade 106. Desirably,reference tube 160 is cylindrical and exceeds the length of the medicaldevice to be reduced in size.

Another embodiment of the invention is illustrated in FIGS. 8 a and 8 b.In the embodiment of FIGS. 8 a and 8 b, two non-rotating plates 156 arepresent, one at each end of the apparatus. Each blade 106 is connectedat first end 174 to a linear slide 154 a via a connecting link 130 a andat second end 178 to a linear slide 154 b via a connecting link 130 b.Linear slide 154 a is mounted on non-rotating plate 156 a and linearslide 154 b is mounted on non-rotating plate 156 b. The presence of thesecond non-rotating plate 156 b, linear slide 154 b and connecting link130 b is optional but contributes to providing a rigid frame upon whichthe connecting links and associated blades may slide withoutmisalignment relative to the reference circle.

FIGS. 8 a and 8 b illustrate the use of the inventive apparatus invarious stages of the size reduction process. In FIG. 8 a, stent 180 hasbeen placed in tubular aperture 162 which is characterized by a diameterd₁. In FIG. 8 b, the device has been actuated by rotating actuationplate 142 so as to move blades 106 inward. Aperture 162, as shown inFIG. 8 b is characterized by a diameter d₂ which is reduced relative todiameter d₁. Stent 180 is seen to be of reduced diameter relative to itsprevious diameter as shown in FIG. 8 a.

FIG. 8 c differs from FIG. 8 b, only in that stent 180 has been crimpedonto catheter 184 in FIG. 8 c.

Blades 106 may be made of any suitable, hard material including hardenedsteel. Desirably, the blades will be made of a material such as zirconiaceramic. Blades made of zirconia ceramic may be used withoutlubrication. Furthermore, because of their low thermal conductivity,they may be used to create a highly insulated chamber suitable forcryogenic processing of martensite in nitinol stents.

Such an embodiment is shown in FIG. 9. Stent 180 is disposed betweenblades 106 which can move inward in the direction of the arrows. Blades106 are cooled by a first source of cooling fluid 184 located at firstend 174 of blades 106. Although not shown, a second source of coolingfluid may be provided at second end 178 of blades 106 as well. Thecooling fluid may be a liquid cryogenic. Exemplary cryogenics includeliquid nitrogen, argon or carbon dioxide although other cryogens mayalso be used. The cooling fluid may also be a chilled gas such as air.The cooling fluid may also be a cooled inert gas such as nitrogen, argonor other inert gasses.

The aperture formed by the blades is a highly insulated chamber which issuitable for cryogenic processing of martensite in nitinol stents. Thechamber is maintained at −80° C. and a nitinol stent inserted therein.Upon equilibration of the temperature of the stent, the blades are movedinward to reduce the diameter of the stent. The stent is thus reduced indiameter while being maintained in the martensitic state.

The embodiment of FIG. 9 further has a loading plunger 188 for loading astent or other suitable medical device into the aperture. A sheathhousing 192 which houses sheath 196 is provided at second end 178 ofblades 106. Plunger 188 may be further used to transfer the stent afterit has been reduced in diameter or size to sheath 196. Desirably, sheath196 will have a slightly larger diameter than stent 180 followingreduction in size of the stent. More desirably, the fit of the stentwithin the sheath will be within about 1/32″ and even more desirably,within about 1/64″.

Where lengthy stents or other medical devices are to be reduced in size,the invention contemplates using one of the above described apparatuseswith long blades to accommodate the stent. As an alternative, theinvention also contemplates disposing two or more of such apparatusessequentially to form one long aperture. The two or more apertures maythen be reduced in size simultaneously or consecutively.

The arrangement of FIG. 10 shows an embodiment with three devices 100a-c arranged sequentially. A stepped reduction in size may be achievedby placing a stent 180 or similar medical device in the apparatus andindependently reducing each aperture 118 a-c to a desired size. To thatend, the invention may provide particular utility in manipulatingbifurcated stents or other stents whose diameter varies along itslength. The embodiment of FIG. 10 shows the end portions of the stentbeing reduced in size prior to the middle portion of the stent. Thedevice may also be operated so as to reduce the middle portion in sizeprior to the end portions or in any other sequence.

The invention contemplates yet another approach to reducing the diameterof lengthy stents or similar medical devices, namely walking the stentthrough the apparatus. This may be accomplished by either moving thestent relative to the apparatus or moving the apparatus relative to thestent as shown schematically in FIG. 11. To that end, stent 180 isinserted in device 100. Aperture 118 a is reduced in size with blades106 a in turn reducing portion 180 a of stent 180 in size. Aperture 118a is then opened and aperture 118 b reduced in size thereby reducingportion 180 b of stent 180. Simultaneously, or shortly thereafter,sheath 196 is pushed by plunger 188 over the portion of the stent thathas been reduced in size. Aperture 118 b is opened and the stentadvanced in the apparatus. The process is repeated until the entirelength, or the desired portion of the stent or medical device is reducedin size.

The reduction in size of the stent or other medical device may occur aspart of a precrimping step or it may occur as part of crimping a stentonto a catheter and desirably, onto a balloon disposed about a catheter.In a general sense, it may be used for manipulating a medical device andspecifically, for applying a radial inward force to a medical device.

In another embodiment, the invention is directed to a method ofmanipulating a medical device. As part of the method, a medical devicesuch as those disclosed above is provided. The device has at least threeblades capable of applying a radial inward force. The blades aredisposed about a reference circle to form a shrinkable aperture. Theblades are constructed and arranged such that each blade has only asingle point which a) lies on the circumference of the reference circleprior to movement of the blade, and b) is moved along a radius of thereference circle on movement of the blade. The medical device is placedinto the shrinkable aperture and the blades simultaneously moved inwardto apply a radial inward force to the medical device and thereby reducethe medical device in size, and desirably, in diameter. Followingreduction in size of the medical device, the blades are simultaneouslymoved outward and the medical device removed from the aperture.

The inventive apparatus may also be incorporated into a blow moldingtool to provide a variable size balloon mold as shown generally at 100in FIG. 12. The various parts of the apparatus of FIG. 12 have beendiscussed in conjunction with FIGS. 8 a-c and, with exception of balloon181 and mold cavity ends 193, the reference numerals used in FIG. 12correspond to those used for FIGS. 8 a-c. Mold cavity ends 193 maybeprovided in a variety of sizes and lengths to contain the balloon ateach end. Desirably, the end molds will be adjustably mounted to aportion of the apparatus such as fixed plates 156 to provide for anadjustable length balloon mold.

The invention is also directed to a method for molding a medical balloonusing the inventive apparatus described above. A balloon preformprepared through any standard method is provided. The inventive mold,shown generally at 100 is also provided. Balloon 181 is inserted intoaperture 162. Aperture 162 is optionally reduced to a predetermined sizeand the preform expanded using standard techniques. An inflation fluid,for example, may be supplied to the preform and the preform expanded andheated. The balloon in its expanded state is shown in FIG. 12.

More generally, the invention may be practiced by providing at leastthree movable blades disposed about a reference tube to form ashrinkable tubular aperture. The blades are constructed and arrangedsuch that each blade has a single line which a) lies on the surface ofthe reference tube prior to movement of the blade, and b) is moved alonga radial plane of the reference tube on movement of the blade. A balloonpreform is placed into the shrinkable aperture. The aperture may be setat a predetermined size prior to or following insertion of the balloontherein. An inflation fluid is provided and the balloon preform inflatedso that the preform expands to the size of the aperture. The preform maybe heated during this inflation/blowing step. The inflation fluid isthen removed from the thus formed balloon and the balloon removed fromthe apparatus.

The balloon may also be molded in accordance with the method describedin U.S. Pat. No. 5,163,989, or in accordance with other methods as areknown to those of ordinary skill in the art, substituting the instantapparatus for the standard balloon mold. Other patents which discussballoon molding include U.S. Pat. No. 5,807,520. Other referencesillustrating the materials and methods of making catheter balloonsinclude: U.S. Pat. No. 4,413,989 and U.S. Pat. No. 4,456,000 toSchjeldahl et al, U.S. Pat. No. 4,490,421, U.S. Re 32,983 and Re 33,561to Levy, and U.S. Pat. No. 4,906,244, U.S. Pat. No. 5,108,415 and U.S.Pat. No. 5,156,612 to Pinchuck et al.

The use of the inventive apparatus as a mold allows for the blowing of aballoon to a predetermined size using a single adjustable size balloonmold thereby eliminating the need to have multiple molds of differentsizes.

The invention further contemplates molding a balloon to a desired shapeusing a plurality of the inventive devices arranged sequentially. As anexample of this, shown in FIG. 13, a stepped balloon 181 maybe preparedby arranging several devices 100 a, 100 b and 100 c sequentially. Aballoon preform is inserted in the aperture formed by the device. Theaperture of each device may be preset at a desired size or may bereduced in size to a predetermined size after the balloon preform isinserted therein. The balloon may then be blow molded in accordance withany suitable blow molding technique known in the art.

The invention is also understood to be directed to embodiments employingvarious combinations of the features disclosed herein.

The above disclosure is intended to be illustrative and not exhaustive.This description will suggest many variations and alternatives to one ofordinary skill in this art. All these alternatives and variations areintended to be included within the scope of the attached claims. Thosefamiliar with the art may recognize other equivalents to the specificembodiments described herein which equivalents are also intended to beencompassed by the claims attached hereto.

What is claimed is:
 1. A method of manufacturing a medical device,comprising: providing an apparatus including a plurality of movableblades arranged around a reference circle to define a variable diameteraperture, each movable blade including first and second surfacesconverging at a tip, the first surface of any one of the plurality ofmovable blades facing a second surface of an adjacent one of theplurality of movable blades; placing a medical balloon within theaperture; actuating the apparatus to reduce the diameter of the aperturewith the balloon positioned in the aperture; and heating the balloonwhile the balloon is positioned in the aperture.
 2. The method of claim1, further comprising: inflating the balloon with an inflation fluidwhile the balloon is positioned in the aperture.
 3. The method of claim2, wherein the balloon is heated while inflating the balloon.
 4. Themethod of claim 2, wherein the balloon is inflated to the diameter ofthe aperture.
 5. The method of claim 1, wherein the first surface ofeach blade is tangent to the reference circle when the aperture is in anexpanded configuration.
 6. The method of claim 5, wherein the firstsurface of each blade remains tangent to the reference circle while theapparatus is actuated to reduce the diameter of the aperture.
 7. Themethod of claim 1, wherein the apparatus applies a radially inward forceon the balloon positioned in the aperture.
 8. The method of claim 1,wherein the first and second surfaces of each blade are flat surfaces.9. The method of claim 1, wherein the apparatus includes an actuationmechanism coupled to each of the plurality of movable blades, and theactuation mechanism is rotated to simultaneously actuate the pluralityof movable blades to reduce the diameter of the aperture.
 10. A methodof manufacturing a device for use in a medical procedure, comprising:providing an apparatus including a plurality of movable blades arrangedaround a reference circle to define a variable diameter aperture, theapparatus including an actuation mechanism for simultaneously actuatingthe plurality of movable blades from a first position in which theaperture has a first diameter to a second position in which the aperturehas a second diameter less than the first diameter; placing a medicaldevice within the aperture with the plurality of movable blades in thefirst position; actuating the actuation mechanism to simultaneously movethe plurality of movable blades to the second position to reduce thediameter of the aperture with the medical device positioned in theaperture; and heating the medical device while the medical device ispositioned in the aperture.
 11. The method of claim 10, wherein themedical device is a medical balloon.
 12. The method of claim 11, furthercomprising: inflating the balloon with an inflation fluid while theballoon is positioned in the aperture.
 13. The method of claim 12,wherein the balloon is heated while inflating the balloon.
 14. Themethod of claim 12, wherein the balloon is inflated to the diameter ofthe aperture.
 15. The method of claim 10, wherein the apparatus appliesa radially inward force on the medical device positioned in theaperture.
 16. The method of claim 10, wherein each movable bladeincludes first and second surfaces converging at a tip, the firstsurface of each blade facing the aperture and being tangent to thereference circle.
 17. The method of claim 16, wherein the first surfaceof any one of the plurality of movable blades slides along a secondsurface of an adjacent one of the plurality of movable blades as theapparatus is actuated to reduce the diameter of the aperture.
 18. Themethod of claim 10, wherein the actuation mechanism is coupled to eachof the plurality of movable blades.
 19. The method of claim 18, whereinthe actuation mechanism is rotated to reduce the diameter of theaperture.